SEBASTIAN INLET — The lure of saltwater fishing, boating, surfing and swimming draws millions of visitors to Sebastian Inlet State Recreation Area each year, making it the second most popular park in Florida.

Camping and picnicking sites are available at the 576-acre park that straddles the Brevard and Indian River county line. On the south side, 51 campsites are available; 55 sites are on the Brevard side.

Fishing poles and tackle can be rented at the concession stand on the north side of the park; food also is available there.

But before you go to the inlet park that trails only Honeymoon Island near Clearwater in popularity, it pays to know a few things.

Four boats sank in the inlet over the Memorial Day weekend, said park ranger Terry O'Toole. Strong currents in the inlet between the Indian River and the ocean change with the tides and can wreak havoc with small boats, he said.

''The typical victims are families who are used to boating in lakes,'' O'Toole said. ''These people go out in their small, overloaded freshwater crafts, get caught in big 6-foot swells at the mouth of the inlet and sink, especially when the current is flowing out to sea.''

O'Toole advises people to use only ocean-going vessels when venturing through the inlet. ''And if you do go out, stay close to the northern jetty,'' he said.

Surfers flock to the inlet from all over Florida because of the area's big waves. Although thrill-seekers love them, these waves and their companion currents can be deadly, O'Toole said.

''We have riptides here that carry people a long way offshore in no time,'' he said. ''The important thing to remember if you're caught in one is not to panic and don't fight the current. Just allow the current to take you until it weakens and then paddle back to the beach at an angle.''

Large waves also can threaten fishermen on the jetties. Warning signs are posted, but seem to be ignored by people as they cast their lines for sea bass, snook, blue fish, snapper, whiting and other fish that abound near the inlet. In rough seas, however, the signs should be heeded because large waves can wash people off the jetty and throw them against nearby rocks.

Portuguese man-of-war frequent the beach during summer months. If touched, the purple, blue and pink creatures leave stinging remembrances of a day by the ocean. O'Toole recommends spraying stings with a mixture of ammonia and water, which is available at ranger offices.

Stingrays thrive in the river and sometimes get snagged in fishing lines or trampled by clammers.

''Stingrays give a pretty painful sting,'' O'Toole said. ''It's a one-time experience because you never want it to happen again.''

People who are stung by stingrays are taken to the hospital because the ray's barb usually remains imbedded in the skin and must be removed by a doctor, he said.

For visitors who want to be well-informed about potential dangers at the park, rangers offer slide shows and tours for groups. Reservations to view ''A Coward's Guide: Things to Avoid in Nature'' and presentations on poisonous plants can be made by calling the rangers at 727-1752.